SEARCH · Search NASA

Results for “Log data”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 361 records · Page 20

All sources NASA NTRS DOE OSTI

NASA NTRS1995

Gaussian statistics of the cosmic microwave background: Correlation of temperature extrema in the COBE DMR two-year sky maps

We use the two-point correlation function of the extrema points (peaks and valleys) in the Cosmic Background Explorer (COBE) Differential Microwave Radiometers (DMR) 2 year sky maps as a test for non-Gaussian temperature distribution in the cosmic microwave background anisotropy. A maximum-likelihood analysis compares the DMR data to n = 1 toy models whose random-phase spherical harmonic components a(sub lm) are drawn from either Gaussian, chi-square, or log-normal parent populations. The likelihood of the 53 GHz (A+B)/2 data is greatest for the exact Gaussian model. There is less than 10% chance that the non-Gaussian models tested describe the DMR data, limited primarily by type II errors in the statistical inference. The extrema correlation function is a stronger test for this class of non-Gaussian models than topological statistics such as the genus.

Kogut, A.↗

NASA NTRS1983

A multiwavelength study of the short-period cataclysmic variable V442 Ophiuchi

The results of a program of observations of the cataclysmic variable V442 Oph from UV to IR wavelengths are reported. The observations comprise IUE SWP and LWR-camera spectra from October, 1981; UBVr and R photometry at Manastash Ridge Observatory from August, 1980; UBV photometry and IR measurements at Kitt Peak from July, 1981; and Coudespectroscopy at Mt. Wilson from June, 1980, and at Mt Lemmon from July, 1982. Tables of data, plots of H-alpha and He-II radial velocity, sample spectra, light curves, and a log-log diagram of F(lambda) vs lambda are given. Flux-ratio analysis of the IR data indicates a disk with very little optically thin material anad an outer-edge temperature of about 7920 K. The calculated period (3.37 h) and mass-accretion rate (1 x 10 to the -8th solar mass/yr) are compared to those of similar objects, and V442 Oph is found to be similar in this respect to systems like H2252-035. Its lack of a rotational period and the weakness of the optical and UV line emissions, however, are more like the old nova V603 Aql.

Shafter, A. W.↗

NASA NTRS1986

Preliminary geological investigation of AIS data at Mary Kathleen, Queensland, Australia

The Airborne Imaging Spectrometer (AIS) was flown over granitic, volcanic, and calc-silicate terrain around the Mary Kathleen Uranium Mine in Queensland, in a test of its mineralocial mapping capabilities. An analysis strategy and restoration and enhancement techniques were developed to process the 128 band AIS data. A preliminary analysis of one of three AIS flight lines shows that the data contains considerable spectral variation but that it is also contaminated by second-order leakage of radiation from the near-infrared region. This makes the recognition of expected spectral absorption shapes very difficult. The effect appears worst in terrains containing considerable vegetation. Techniques that try to predict this supplementary radiation coupled with the log residual analytical technique show that expected mineral absorption spectra can be derived. The techniques suggest that with additional refinement correction procedures, the Australian AIS data may be revised. Application of the log residual analysis method has proved very successful on the cuprite, Nevada data set, and for highlighting the alunite, linite, and SiOH mineralogy.

Huntington, J. F.↗

NASA NTRS1995

EUVE observations of Algol: Detection of a continuum and implications for the coronal (Fe/H) abundance

We report results from the first extreme ultraviolet spectrum of the prototypical eclipsing binary Algol (beta Per), obtained with the spectrometers on the Extreme Ultraviolet Explorer (EUVE). The Algol spectrum in the 80-350 A range is dominated by emission lines of Fe XVI-XXIV, and the He II 304 A line. The Fe emission is characteristic of high-temperature plasma at temperatures up to at least log T approximately 7.3 K. We have successfully modeled the observed quiescent spectrum using a continuous emission measure distribution with the bulk of the emitting material at log T greater than 6.5. We are able to adequately fit both the coronal lines and continuum data with a cosmic abundance plasma, but only if Algol's quiescent corona is dominated by material at log T greater than 7.5, which is physically ruled out by prior X-ray observations of the quiescent Algol spectrum. Since the coronal (Fe/H) abundance is the principal determinant of the line-to-continuum ratio in the EUV, allowing the abundance to be a free parameter results in models with a range of best-fit abundances approximately = 15%-40% of solar photospheric (Fe/H). Since Algol's photospheric (Fe/H) appears to be near-solar, the anomalous EUV line-to-continuum ratio could either be the result of element segregation in the coronal formation process, or other, less likely mechanisms that may enhance the continuum with respect to the lines.

Stern, Robert A.↗

DOE OSTI2024

Synthesizing realistic sand assemblies with denoising diffusion in latent space

Abstract The shapes and morphological features of grains in sand assemblies have far‐reaching implications in many engineering applications, such as geotechnical engineering, computer animations, petroleum engineering, and concentrated solar power. Yet, our understanding of the influence of grain geometries on macroscopic response is often only qualitative, due to the limited availability of high‐quality 3D grain geometry data. In this paper, we introduce a denoising diffusion algorithm that uses a set of point clouds collected from the surface of individual sand grains to generate grains in the latent space. By employing a point cloud autoencoder, the three‐dimensional point cloud structures of sand grains are first encoded into a lower‐dimensional latent space. A generative denoising diffusion probabilistic model is trained to produce synthetic sand that maximizes the log‐likelihood of the generated samples belonging to the original data distribution measured by a Kullback‐Leibler divergence. Numerical experiments suggest that the proposed method is capable of generating realistic grains with morphology, shapes and sizes consistent with the training data inferred from an F50 sand database. We then use a rigid contact dynamic simulator to pour the synthetic sand in a confined volume to form granular assemblies in a static equilibrium state with targeted distribution properties. To ensure third‐party validation, 50,000 synthetic sand grains and the 1542 real synchrotron microcomputed tomography (SMT) scans of the F50 sand, as well as the granular assemblies composed of synthetic sand grains are made available in an open‐source repository.

Vlassis, Nikolaos N.↗

NASA NTRS2008

SWIFT BAT Survey of AGN

We present the results1 of the analysis of the first 9 months of data of the Swift BAT survey of AGN in the 14-195 keV band. Using archival X-ray data or follow-up Swift XRT observations, we have identified 129 (103 AGN) of 130 objects detected at [b] > 15deg and with significance > 4.8-delta. One source remains unidentified. These same X-ray data have allowed measurement of the X-ray properties of the objects. We fit a power law to the logN - log S distribution, and find the slope to be 1.42+/-0.14. Characterizing the differential luminosity function data as a broken power law, we find a break luminosity logL*(ergs/s)= 43.85+/-0.26. We obtain a mean photon index 1.98 in the 14-195 keV band, with an rms spread of 0.27. Integration of our luminosity function gives a local volume density of AGN above 10(exp 41) erg/s of 2.4x10(exp -3) Mpc(sup -3), which is about 10% of the total luminous local galaxy density above M* = -19.75. We have obtained X-ray spectra from the literature and from Swift XRT follow-up observations. These show that the distribution of log nH is essentially flat from nH = 10(exp 20)/sq cm to 10(exp 24)/sq cm, with 50% of the objects having column densities of less than 10(exp 22)/sq cm. BAT Seyfert galaxies have a median redshift of 0.03, a maximum log luminosity of 45.1, and approximately half have log nH > 22.

Tueller, J.↗

DOE OSTI2024

Accurate field-level weak lensing inference for precision cosmology

We present miko, a catalog-to-cosmology pipeline for general flat-sky field-level inference, which provides access to cosmological information beyond the two-point statistics. In the context of weak lensing, we identify several new field-level analysis systematics (such as aliasing, Fourier mode-coupling, and density-induced shape noise), quantify their impact on cosmological constraints, and correct the biases to a percent level. Next, we find that model misspecification can lead to both absolute bias and incorrect uncertainty quantification for the inferred cosmological parameters in realistic simulations. The Gaussian map prior infers unbiased cosmological parameters, regardless of the true data distribution, but it yields overconfident uncertainties. The log-normal map prior quantifies the uncertainties accurately, although it requires careful calibration of the shift parameters for unbiased cosmological parameters. Here, we demonstrate systematics control down to the 2% level for both models, making them suitable for ongoing weak lensing surveys.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2025

Detecting Living-off-the-land Attacks Using K-means And Graph Convolutional Networks

The code ingests Zeek logs derived from network packet captures and goes through data preprocessing before it gets passed into a K-Means model that labels each device as either a client or server. Graph Convolutional Network (GCN) model is used to obtain the embeddings to represent the features in lower dimension. Last, K-means cluster analysis is used to cluster the embeddings for each class.

Quach, Anna [Idaho National Laboratory (INL), Idah↗

DOE OSTI2025

Upland tidal brackish marsh specific conductivity and salinity measurements, PIE LTER, Plum Island Sound, MA, 2023

This dataset includes raw and corrected specific conductivity, temperature, and calculated salinity measurements collected at 10 cm depth in a Typha angustifolia-dominated tidal brackish wetland at the upper estuary of Plum Island Sound in Newbury, Massachusetts (MA) within the Plum Island Ecosystems Long Term Ecological Research (PIE LTER) site. Measurements were taken to evaluate temporal variation in porewater salinity (a proxy for porewater sulfate concentration) in high frequency to assess soil and plant responses to changes in salinity. Measurements were collected using an Onset HOBO U24-002 Saltwater Conductivity/Salinity data logger deployed in a well. Specific conductivity was corrected using non-linear temperature compensation, and salinity was calculated using the Practical Salinity Scale 1978 via Onset's HOBOware software. Reference conductivity measurements to correct for sensor drift were taken at the start and end of each deployment using a HACH HQ14D Portable Conductivity Meter. Data were then filtered in MATLAB to remove values logged while the sensor was out of the well or during post-deployment equilibration. Detailed metadata, including variable descriptions, sampling methods, QA/QC procedures, and site information, are provided in the files: Typha_ctd_salinity_dd.csv and Typha_MI_ctd_salinity_2023_flmd.csv.

54 ENVIRONMENTAL SCIENCES↗

DOE OSTI2025

Upland tidal brackish marsh specific conductivity and salinity measurements, PIE LTER, Plum Island Sound, MA, May-December 2022

54 ENVIRONMENTAL SCIENCES↗

DOE OSTI2025

FY 2025 Multidimensional Data Correlation Platform: Unified Software Architecture for Advanced Materials and Manufacturing Technologies Data Management and Processing

The Advanced Materials and Manufacturing Technologies (AMMT) program continues to advance a data-driven approach to demonstrate the utility of additive manufacturing for fabricating components for nuclear applications. A key scientific goal is to leverage data to better understand manufacturing outcomes and thereby improve the performance, reliability, and lifespan of nuclear components. Ultimately, this effort supports the development of standards for certification and qualification of additively manufactured components, enabling broader industry adoption. In support of this objective, the AMMT program is building and deploying a data management platform to record, index, analyze, and make available the manufacturing data generated across the AMMT program. In FY 2023, the team conceptualized the architecture of the platform and, in FY 2024, deployed the first functional version at the Oak Ridge National Laboratory (ORNL) Manufacturing Demonstration Facility (MDF). In FY 2025, the platform was officially opened to all AMMT members. To enable this expansion, core modifications and enhancements were developed, including improvements to the user interface and workflows for data entry and retrieval. Most notably, robust security and access control mechanisms were implemented to protect data and manage information sharing. This effort featured a logging system, protected views, and controlled access mechanisms. This report documents these enhancements and the transition of the platform into program-wide use.

36 MATERIALS SCIENCE↗

NASA NTRS1977

Report on the lunar ranging at McDonald Observatory

Range measurements to an accuracy of 5 cm were achieved following improvements in the laser oscillator configuration and the photomultiplier system. Modifications to the laser include a redesigned pockel cell mount to eliminate stressing of the cell crystal; an improved electrically triggered spark gap for sharpening the electrical pulse; the use of a brewster plate in the cavity to eliminate pre-pulsing; improved alignment for the oscillator system; and increased cavity lifetime through thin film polarizer technology. Laser calibration data are presented along with the lunar laser operations log for June to October 1977.

Silverberg, E. C.↗

NASA NTRS1978

Evidence for a primordial magnetic field during the meteorite parent body era

Data on 247 meteorites were examined, and a log-log plot of the magnetic moment/gm versus the susceptibility/gm reveals a straight-line relation with a slope of unity for a range of meteorite types extending from achondrites at the low Fe-Ni end to stony-irons. The relation holds for a span of parameter values ranging between four and five orders. The results support the hypothesis of a common background magnetic field at the time of meteorite formation. An equation relating the primordial field strength to the average carrier demagnetization factor, which can vary from 0 to 4 pi, is presented. The extreme lower limit for the field strength is 0.02 oersted, while for the mean field of 0.27 oersted determined from a study of individual meteorites (Stacy and Banerjee, 1974), the average value for the carrier demagnetization factor is 0.74, corresponding to elongated grains.

Sonett, C. P.↗

NASA NTRS1988

Effects of El Chichon volcanic effluents on stratospheric aerosol dynamics

The effects of El Chichon's April 1982 eruption on stratospheric aerosol dynamics are presently discussed in terms of log-normal size distributions over 15-20 km sample altitudes between 30 and 45 deg N over the contiguous U.S. After collection, samples were studied by SEM, and log-normal size distributions were fitted to the data-points obtained. It is found that stratospheric aerosol behavior is explainable by the laws of aerosol mechanics more easily than has been the case for tropospheric aerosol, for which the source-sink relationship is much more complex.

Pueschel, R. F.↗

NASA NTRS1993

Program Facilitates Distributed Computing

KNET computer program facilitates distribution of computing between UNIX-compatible local host computer and remote host computer, which may or may not be UNIX-compatible. Capable of automatic remote log-in. User communicates interactively with remote host computer. Data output from remote host computer directed to local screen, to local file, and/or to local process. Conversely, data input from keyboard, local file, or local process directed to remote host computer. Written in ANSI standard C language.

Hui, Joseph↗

NASA NTRS1992

The Ptolemaic gamma-ray burst universe

The BATSE experiment on GRO has demonstrated the isotropic arrival directions and flat log N vs log S of cosmic gamma-ray bursts. These data are best explained if the burst sources are distributed throughout an extended spherical galactic halo, as previously suggested by Jennings. The halo's radius is at least 40 kpc, and probably is more than 100 kpc. I consider possible origins of this halo, including primordial formation and neutron stars recoiling from their birthplaces in the galactic disk. A simple geometrical model leads to a predicted relation between the dipole and quadrupole anisotropy. I suggest that neutron stars born with low recoil become millisecond pulsars, while those born with high recoil become the sources of gamma-ray bursts; these populations are nearly disjoint. Quiescent counterparts of gamma-ray bursts are predicted to be undetectably faint.

Katz, J. I.↗

NASA NTRS1994

Extraction Of Emissivities From Thermal Infrared Spectra

Report presents evaluation of two techniques for processing multispectral data. One technique for extraction of emissivity data called "model emittance calculation." Other technique called "thermal log residuals."

Hook, Simon J.↗

NASA NTRS1995

Recent chaqnges in the IUE spectrum of the very young planetary nebula He 3-1357 (=SAO 244567)

We obtained the first high-dispersion IUE spectrum, and an additional low-dispersion spectrum of the very young planetary nebula He 3-1357 and its central star SDAO 244567. In 1988, it showed a very strong C IV lambda-1549 P Cygni profile which diminished and has disappeared by 1994, but C IV absorptions are seen in a high-resolution spectrum. The electron density from the C III F(lambda 1907)/F(lambda 1909) emission ratio is log N(sub e) = 4.1/cc. The older IUE data were reprocessed, and emission-line fluxes vary greatly for the period 1988-1994. The high-dispersion data show a rich Fe V and Fe VI absorption spectrum.

Feibelman, Walter A.↗